HNBs (Home NodeB) are small, low power NodeBs, and are deployed in indoor places such as homes and offices, etc. The main functions of the HNBs are to provide a higher service rate to users and reduce the cost required to use high rate services, and make up for the deficiency of coverage of existing distributed cellular wireless communication systems. Advantages of the HNBs are material benefit, convenience, low-power output, plug and play, etc.
The HNBs are connected to a core network through a HNB AN (Home NodeB Access Network), wherein the HNB AN is composed of HNBs (Home NodeB) and HNB GWs (Home NodeB Gateway). The functions primarily performed by the HNB GWs include verifying the security of the HNBs, dealing with the registration and access control of the HNBs, and being responsible for exchanging data between the core network and the HNBs.
A HNB management system (HMS) performs operation, maintenance and management on the HNBs, configures and controls the HNBs according to operator requirements, and primarily implements configuration management function for the HNBs, including verifying position information, performing parameter configuration on the HNBs, and primarily designing parameter configuration to the CN-level, parameter configuration of the Radio Access Network (RAN) side and parameter configuration of RF. A management system corresponding to an evolved home NodeB (HeNB) is HeMS, and a HNB gateway is a HeNB GW. The HeNB may be connected to a Mobility Management Entity (MME) directly without through the HeNB GW. FIG. 1 illustrates a structural diagram of a LTE system network where HeNBs are introduced.
With the development of the HNB technologies, a close subscriber group (CSG) concept is introduced which is used to manage subscriber groups. With the introduction of the CSG concept, the concept for a CSG cell access mode is introduced in HNBs. There are three CSG access modes for the HNBs, an open access mode, a close access mode, and a hybrid access mode. A HNB with the open access mode allows access of subscribers and non-subscribers, and has no difference from a normal macro cell. A HNB with the close access mode merely allows access of subscriber subscribing to the CSG. Although a HNB with the hybrid access mode allows access of both subscribers and non-subscribers, the subscribers are superior to the non-subscribers. On the premise of resource shortage, the HNBs preferentially serve the subscribers, and may switch the non-subscribers to other cells or release signaling connection thereof.
eNBs belonging to the same MME typically will set up an X2 connection. A User Equipment (UE) with an X2 connection between the eNBs may decrease handoff delay using X2 handoff, and decrease signaling interaction with the MME. HeNBs, which are terminal UEs, not only have the characteristics, such as plug-and-play, but also are numerous and have uncertainty, from the perspective of network topology. Therefore, unlike traditional network systems, HeNB networks cannot perform pre-configuration of neighbor cells. Further, setup of a direct interface connection between the HeNBs has some limitations relative to traditional networks. Thus, the direct interface between the HeNBs is preferably applied in a particular scene, such as the deployment of enterprise level HeNBs, setup of a direct interface in the scene of the same CSG deployment, and a scene of an Intra-GW. Support of the direct interface between the HeNBs will bring some benefits, for example, handoff of the UE between the HeNBs will be implemented without bypassing the MME, thereby speeding up handoff speed, transfer of interference coordination parameters between the HeNBs, and setup and update of a relationship between neighbor cells, etc., and facilitating implementation of HeNB Self Organization Network (SON) functions.
In summary, there is a need for setup of the direct interface between the HeNBs. For the HeNBs which are CSG cells, CSG information can be used as a reference to set up the direct interface. In order to ensure that the HeNBs with the same CSG attribute can set up the direct interface between them under the same HeNB GW, they needs to obtain the CSG information of each other before setting up the direct interface. Therefore, the HeNBs obtaining the CSG information of each other before setting up the direct interface is beneficial to determination of setup of the direct interface, and is also a means for obtaining information of neighbor cells.